A prevalent tube or hose construction comprises one or more elongated strips which are helically wound about an axis and bonded at adjacent convolutions into tubular form. A number of such hoses incorporate electrical conductors and, many times, the conductors are extruded or otherwise formed into the elongated strip or strips prior to the time when the strip is convoluted helically into tubular shape.
Such convoluting creates great tensile and compressive forces which are exerted upon the conductor. As a consequence, the conductor may be stretched beyond its elastic limit and broken or, alternatively, the conductor is compressed tending to bunch it up. In addition, when the hose is bent, various portions of the hose are either compressed, or placed in tension. This further tension and compression may create further stresses on, or fatigue, the conductor and thus cause it to break.
In order to prevent breakage of the conductors, it is conventional to utilize a wire which is sufficiently massive to withstand breakage under such tension and compression. The massiveness of the wire can force the plastic of the hose to yield instead of the wire. In similar or other cases, stranded wire has been specified and single wire prohibited because stranded wire, having a twist to it, will yield and tend to untwist and lengthen upon application of tensile loads thereon to avoid breaking.
All such solutions have a common disadvantage in that they require a minimum wire gauge sufficient to resist or compensate for such forces. Thus, the gauge or number of wires is generally greater than that required by the power requirements. As a result, the amount of material and the cost of the hose is increased. Also, it flexibility is decreased.